This invention relates to compositions that contain mixtures of heavy hydrocarbons, such as bitumen bases and polymers of the thermoplastic polyolefin type, also called bitumen-polymer type bituminous compositions in the remainder of this description. The invention also relates to the preparation of such compositions and their applications in the paving industry, in particular in the construction of roadways, and in other industries, in particular as sealing coats for roofs, insulation boards or anti-corrosion coatings.
It is known that heavy hydrocarbons, identified in the remainder of this description by the term bitumen(s), can be produced, in particular, from crude oil, by distilling the latter and deasphalting the heavy fraction produced by the distillation(s). Based on the origin of the crude oil, the bitumen consists of variable percentages of paraffinic (aliphatic or naphtenic) or aromatic oils, of resins and of asphaltenes (refer to EP-B-246 956).
Based on its constitution, the bitumen may have a character that is more or less thermoplastic. It softens under the effect of heat, its point of softening, commonly called "ball-ring"temperature (BRT) because of the method used in determining it (in accordance with NFT standard 66-008), can, based on the procedure used in obtaining the bitumen, vary between approximately 30 and approximately 130.degree. C.
The behaviors of these bitumens may be judged as insufficient for certain applications that require either good properties when cold, such as:
resistance to shrinking and cracking when cold, for anti-rutting layers of roads, PA1 bending when cold, for sealing materials, PA1 resistance to fluage at high temperatures, in the application of sealing coat construction, PA1 elastic behavior PA1 endurance of certain sealants when heated, during certain treatments (bodies of cars). PA1 1) the oxidation of the bitumen using the blowing technique with air at approximately 250.degree. C. The product so obtained can present high "ball-ring" temperatures. It is hard and more brittle. PA1 2) The modification of the bitumen by incorporating SBR (styrene-butadiene-rubber) type polymers, for example, vulcanisable or not, in particular using sulfur (or sulfur donors) or peroxides. This technique requires high and perfectly controlled temperatures over relatively long periods of time. The product so obtained also has a very high viscosity, not very compatible with the procedures of implementation used in the profession. Furthermore, the vulcanization gives the bitumen an irreversible character, not very favorable to an easy implementation. PA1 3) The modification of the bitumen by incorporating certain polyolefin type polymers, such as, in particular, polyethylene. The product's "ball-ring" temperatures can reach values of 100.degree. C., this product has mediocre elasticity properties and a high viscosity. PA1 a) a mostly atactic propylene homopolymer, PA1 b) an amorphous propylene and alpha-olefin copolymer in C4-C10 and PA1 c) an amorphous propylene and ethylene copolymer where the a) and b) polymers have an intrinsic viscosity that is greater than 1 dl/g. PA1 a content of at least 1% by weight of a thermoplastic polyolefin, whose crystallinity rate is greater than or equal to 35%, PA1 a melting point that is greater than or equal to 110.degree. C., PA1 a penetrability at 25.degree. C. that is lesser than or equal to 300 tenths of a millimeter. PA1 a) the heaviest fraction obtained by direct distillation of the crude oil under atmospheric pressure or under reduced pressure; PA1 b) the heavy phase obtained by deasphalting, using a solvent, of a heavy fraction obtained following the procedures described in a); PA1 c) the product of oxidation, in the presence or not of catalysts, of a heavy fraction as set forth in a), or of a heavy phase as set forth in b); PA1 d) the product of oxidation, in the presence or not of catalysts, of a mixture: PA1 e) a mixture of an oxidized product according to b) or c) or of a hard base, and a distillate, or a deasphalted oil, or an aromatic extract obtained in the removal of aromatics from lubricating oils, or of a deasphalting pitch, or of a heavy fraction as set forth in a) or of a heavy phase as set forth in b). PA1 from 1 to 15% by weight and, preferably, approximately 5% by weight, for the paving applications, in particular as anti-rutting coatings for roadway surfaces or as binder courses, PA1 and from 3 to 25% by weight, preferably between 11 and 12% by weight, for the industrial applications, such as the sealing coats for roofs, thermal or sound insulation boards and anti-corrosion coatings. PA1 kinematic viscosity at 100.degree. C.: 615 mm.sup.2 /s, PA1 penetrability at 25.degree. C. in 1/10 mm, according to the NF-T-66004 standard: 500, PA1 softening point (ball-ring temperature or BRT, according to the NF-T-66008 standard): 24.5.degree. C. PA1 density: 0.949, PA1 melt flow index measured at 190.degree. C. under a 2.16 kg charge consistent with ASTM D 1238 standard: 0.5 g/10 mn, PA1 average molecular mass by weight (1): 150 000, PA1 average molecular mass by number (1): 20 000, PA1 increase in temperature from 50 to 200.degree. C. at a rate of 10.degree. C./mn, PA1 5 mn rest at 200.degree. C., then decrease from 200.degree. C. to 50.degree. C. at a rate of 20.degree. C.:mn, and 5 mn rest at 50.degree. C.
or characteristics or workability when hot (controlled viscosity) or of temperature resistance, such as:
Known techniques for improving the resistance of a bitumen when heated include:
It is known that, in the last case, only polyethylene with a low density, meaning less that 0.93, can be used, because only the low density thermoplastic polyolefins, due to their weak crystallinity, can be mixed in a homogenous manner with bitumen.
However, these polyolefins are expensive, and the regulations in force in many countries are now urging the manufacturers to recuperate and/or recycle their thermoplastic waste that consists of polyolefins with various densities.
It is in trying to respect the environment that certain manufacturers have proposed to incorporate this thermoplastic waste in the bitumens, for the traditional applications of paving and industrial bitumens. See, for example, FR-B-2 658 524.
However, due to the mixability problems of certain polymers with bitumen as explained above, these manufacturers are forced to use only amorphous or not very crystalline polymers with an adjusted molecular weight, and, this does not resolve the problem posed by the recuperation of thermoplastic waste of all types.
This is how WO 97/31065 describes a bitumen-polymer mixture, where the polymer is chosen from among:
The content in polymers may vary from 1 to 40% by weight of the bitumen-polymer mixture.
These polymers are almost all non crystalline.
EP-A- 0 816 426 describes a procedure for the manufacture of thermoplastic compositions for sealing, that includes at least one thermoplastic polymer that may be an ethylene copolymer (80 to 97% by weight) and one comonomer, in particular a n-butyl or bitumen acrylate, and one or several pigments, with the mixture of the polymer and the pigment taking place prior to the introduction of the bitumen.
This type of polymer corresponds to amorphous or very weak crystalline products.
U.S. Pat. No. 3,395,110 describes a bitumen-polymer composition that contains between 1 and 20% by weight of an atactic ethylene-propylene copolymer, with a molecular mass whose weight is between 10 000 and 40 000.
This copolymer, obtained by extraction using pentane, as a sub-product of the manufacture of isotactic polypropylene polymers, is amorphous.
During their research work in this field, the applicants established that, surprisingly so, it is possible to incorporate into bitumens the polyolefins that until now were considered as non incorporable in bitumens.